Solar tracker stow system and method

ABSTRACT

A solar tracker system having one or more solar trackers that each include one or more panels and one or more actuators coupled to the one or more panels, the one or more actuators having a first and second vessel; and an electronic control unit configured to inflate the first vessel with fluid from a fluid source and configured to separately inflate the second vessel with fluid from the fluid source. The electronic control unit is configured to determine that a stow event is present based on a first set of environmental data obtained from an environmental sensor that indicates environmental conditions pose a threat to the one or more solar trackers, and in response to determining that the stow event is present, actuate the one or more panels toward a stow configuration target angle by at least inflating the first or second vessels with fluid from the fluid source.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/955,519, filed Apr. 17, 2018, entitled “SOLAR TRACKER CONTROL SYSTEMAND METHOD” having attorney docket number 0105935-005US0, which is anon-provisional of and claims priority to U.S. Provisional Applicationsentitled “PNEUMATIC ACTUATOR SYSTEM AND METHOD” and “PNEUMATIC ACTUATIONCIRCUIT SYSTEM AND METHOD” and “SOLAR TRACKER CONTROL SYSTEM AND METHOD”respectively and having attorney docket numbers 0105935-003PR0 and0105935-004PR0 and 0105935-005PR0 and respectively having applicationNos. 62/486,335, 62/486,377 and 62/486,369. These applications arehereby incorporated herein by reference in their entirety and for allpurposes.

STATEMENT REGARDING FEDERALLY-SPONSORED RESEARCH

This invention was made with Government support under contract numberDE-AR0000330 awarded by DOE, Office of ARPA-E. The Government hascertain rights in this invention.

This application is related to U.S. Non-Provisional application Ser. No.15/955,044 and 15/955,506, filed Apr. 17, 2018 entitled “PNEUMATICACTUATOR SYSTEM AND METHOD” and “PNEUMATIC ACTUATION CIRCUIT SYSTEM ANDMETHOD” respectively, and having attorney docket numbers 0105935-003US0and 0105935-004US0. These applications are hereby incorporated herein byreference in their entirety and for all purposes.

This application is also related to U.S. application Ser. No.15/012,715, filed Feb. 1, 2016, which claims the benefit of U.S.provisional patent application 62/110,275 filed Jan. 30, 2015. Theseapplications are hereby incorporated herein by reference in theirentirety and for all purposes.

This application is also related to U.S. application Ser. Nos.14/064,070 and 14/064,072, both filed Oct. 25, 2013, which claim thebenefit of U.S. Provisional Application Nos. 61/719,313 and 61/719,314,both filed Oct. 26, 2012. All of these applications are herebyincorporated herein by reference in their entirety and for all purposes.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1a and 1b illustrate a respective top perspective and bottomperspective view of a solar tracker in accordance with variousembodiments.

FIG. 2 illustrates a side view of a solar tracker.

FIG. 3 illustrates a side view of an actuator in accordance with oneembodiment, which comprises a V-shaped bottom plate, a planar top-plate,and a set of bellows that are disposed between the top and bottom platesand surrounded by a set of washers.

FIG. 4 illustrates an example of a solar tracking system that includes arow controller that controls a plurality of rows of solar trackers.

FIG. 5 is an exemplary illustration of a set of rows, including a firsttracker and second tracker, with each tracker comprising a plurality ofactuators disposed along a common axis and with each actuator comprisinga first and second bellows.

FIG. 6 is a block diagram of elements of a solar tracking system thatincludes a row controller and a first and second solar tracker.

FIG. 7 illustrates an example of a tracker tracking the position of sunthroughout the day as the sun moves through the sky.

FIG. 8a illustrates an example of a tracker being in a non-idealposition relative to the sun and FIG. 8b illustrates moving the trackerto an ideal position with the tracker axis being coincident with thecenter of the sun.

FIG. 9 illustrates an example method of controlling one or more solartrackers to match the angle or position of the sun.

FIG. 10 illustrates a state diagram associated with controlling one ormore solar trackers.

FIG. 11 illustrates a tracking window that can be used by the whencontrolling one or more solar trackers.

FIG. 12 illustrates a method of identifying a stow event and generatinga stow in one or more tracker.

FIG. 13 illustrates a method 1300 of level-calibrating a solar trackerin accordance with an embodiment.

FIG. 14 is a block diagram of elements of a solar tracking system thatincludes an array controller, a first and second row controller and foursolar trackers.

FIG. 15 illustrates an example embodiment of a row controller featuringa “stow on power loss” function.

It should be noted that the figures are not drawn to scale and thatelements of similar structures or functions are generally represented bylike reference numerals for illustrative purposes throughout thefigures. It also should be noted that the figures are only intended tofacilitate the description of the preferred embodiments. The figures donot illustrate every aspect of the described embodiments and do notlimit the scope of the present disclosure.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIGS. 1a and 1b illustrate respective top perspective and bottomperspective views of a solar tracker 100 in accordance with variousembodiments. FIG. 2 illustrates a side view of the solar tracker 100. Asshown in FIGS. 1a, 1b and 2, the solar tracker 100 can comprise aplurality of photovoltaic cells 103 disposed along a length having axisX₁ and a plurality of pneumatic actuators 101 configured to collectivelymove the array of photovoltaic cells 103. As shown in FIG. 1b , thephotovoltaic cells 103 are coupled to rails 102 that extend alongparallel axes X₂, which are parallel to axis X₁. Each of the pluralityof actuators 101 extend between and are coupled to the rails 102, withthe actuators 101 being coupled to respective posts 104. As shown inFIG. 2, the posts 104 can extend along an axis Z, which can beperpendicular to axes X₁ and X₂ in various embodiments.

As shown in FIG. 2, and discussed in more detail herein, the actuators101 can be configured to collectively tilt the array of photovoltaiccells 103 based on an angle or position of the sun, which can bedesirable for maximizing light exposure to the photovoltaic cells 103and thereby maximizing electrical output of the photovoltaic cells 103.In various embodiments, the actuators 101 can be configured to move thephotovoltaic cells 103 between a plurality of configurations as shown inFIG. 2, including a neutral configuration N where the photovoltaic cells103 are disposed along axis Y that is perpendicular to axis Z. From theneutral configuration N, the actuators 101 can be configured to move thephotovoltaic cells 103 to a first maximum tilt position A, to a secondmaximum tilt position B, or any position therebetween. In variousembodiments, the angle between the neutral configuration N and themaximum tilt positions A, B can be any suitable angle, and in someembodiments, can be the same angle. Such movement can be used toposition the photovoltaic cells 103 toward the sun, relative to an angleof the sun, to reflect light toward a desired position, or the like.

In one preferred embodiment as shown in FIGS. 1a and 1b , a solartracker 100 can comprise a plurality of photovoltaic cells 103 that arecollectively actuated by four actuators 101 disposed along a commonaxis. However, in further embodiments, a solar tracker 100 can compriseany suitable number of actuators 101 including one, two, three, four,five, six, seven, eight, nine, ten, fifteen, twenty, fifty, one hundred,or the like. Similarly, any suitable number of photovoltaic cells 103can be associated with a solar tracker 100 in further embodiments.Additionally, while photovoltaic cells 103 are shown in exampleembodiments herein, in further embodiments, actuators 101 can be used tomove various other objects or structures, including mirrors, reflectors,imaging devices, communications devices, and the like.

FIG. 3 illustrates a side view of an actuator 101 in accordance with oneembodiment. As shown in the example of FIG. 3, the actuator 101comprises a V-shaped bottom plate 310, a planar top-plate 330, and a setof bellows 300 that are disposed between the top and bottom plates 330,310 and surrounded by a set of washers 350. The washers 350 are coupledto a hub assembly 370 that extends between the bottom and top plates310, 330, with the hub assembly 370 defined by a plurality of stackedhub units 373.

The example embodiment of FIG. 3 illustrates the actuator 101 in aneutral configuration N (see FIG. 2), where the top plate 330 extendsalong axis Y, which is perpendicular to axis Z in the neutralconfiguration N. However, as discussed herein, the top plate 330 can beconfigured to tilt to the left and right (or east and west as discussedherein) based on selective inflation and/or deflation of the bellows300. Components of an actuator 101 can comprise various suitablematerials, including metal (e.g., steel, aluminum, iron, titanium, orthe like), plastic or the like. In various embodiments, metal parts canbe coated for corrosion prevention (e.g., hot dip galvanized, pregalvanized, or the like).

A row controller 380 can be operably coupled with bellows 300 of theactuator via pneumatic lines 390. More specifically, an east bellows300E can be coupled to a pneumatic circuit 382 of the row controller 380via an east pneumatic line 390E. A west bellows 300W can be coupled tothe pneumatic circuit 382 of the row controller 380 via a west pneumaticline 390W. A pneumatic control unit 384 can be operably coupled to thepneumatic circuit 382, which can control the pneumatic circuit 382 toselectively inflate and/or deflate the bellows 300 to move the top plate330 of the actuator 101 to tilt photovoltaic cells 103 coupled to thetop plate 330.

For example, as described herein, bellows 300 of an actuator 101 can beinflated and/or deflated which can cause the bellows 300 to expandand/or contract along a length of the bellows 300 and cause movement ofwashers 350 surrounding the bellows 300. Such movement of the washers350 can in turn cause rotation, movement or pivoting of the hub units373 of the hub assembly 370. Such pivoting of hub units 373 of the hubassembly 370 can be generated when a solar tracker 100 is moving betweena neutral position N and the maximum tilt positions A, B as shown inFIG. 2.

As shown in FIG. 3, a bellows 300 can comprise a convoluted body definedby repeating alternating valleys 302 and peaks 304 extending between afirst and second end of the bellows 300. In various embodiments, abellows 300 can be generally cylindrical about a central axis alongwhich the bellows 300 extend. In various embodiments, the bellows 300and portions thereof can have one or more axes of symmetry about acentral axis. For example, in various embodiments, the convolutions ofthe bellows 300 can have circular radial symmetry and/or axial symmetryabout a central axis between the first and second ends or at least aportion thereof. However, as shown in FIG. 3, the bellows 300 can beheld within an actuator 101 in a curved configuration such that theportion of the bellows 300 proximate to the hub assembly 370 iscompressed compared to the portion of the bellows that is distal fromthe hub assembly 370.

In various embodiments, the bellows 300 can be configured to expandalong the length of the bellows 300 when fluid is introduced into thehollow bellows 300 or when the bellows 300 are otherwise inflated.Accordingly, the bellows 300 can be configured to contract along thelength of the bellows 300 when fluid is removed from the hollow bellows300 or when the bellows 300 are otherwise deflated.

Where bellows 300 are configured to expand lengthwise based on increasedpressure, fluid or inflation and configured to contract lengthwise basedon decreased pressure, fluid or inflation, movement of the photovoltaiccells 103 via one or more actuators 101 can be achieved in various ways.For example, referring to the example of FIG. 3, rotating thephotovoltaic cells 103 west (i.e., to the right in this example) can beachieved via one or more of the following:

TABLE 1 Examples of Actions to Rotate Actuator 101 West East Bellows300E West Bellows 300W Result Increase Pressure Maintain Pressure RotateWest Increase Pressure Reduce Pressure Rotate West Maintain PressureReduce Pressure Rotate West Decrease Pressure Decrease Pressure MoreThan Rotate West East Bellows 300E Increase Pressure Increase PressureLess Than Rotate West East Bellows 300E

Referring again to the example of FIG. 3, rotating the photovoltaiccells 103 east (i.e., to the left in this example) can be achieved viaone or more of the following:

TABLE 2 Examples of Actions to Rotate Actuator 101 East East Bellows300E West Bellows 300W Result Maintain Pressure Increase Pressure RotateEast Reduce Pressure Increase Pressure Rotate East Reduce PressureMaintain Pressure Rotate East Decrease Pressure More Than DecreasePressure Rotate East West Bellows 300W Increase Pressure Less ThanIncrease Pressure Rotate East West Bellows 300W

Accordingly, in various embodiments, by selectively increasing and/ordecreasing the amount of fluid within bellows 300E, 300W, the top plate330 and photovoltaic cells 103 can be actuated to track the location orangle of the sun.

While various embodiments of an actuator 101 can include two bellows300E, 300W, further embodiments can comprise a single bellows 300 or anysuitable plurality of bellows 300. In various embodiments, actuators 101include orifices which equalize the flow among many actuators 101,and/or limit the rate of motion as discussed herein.

Turning to FIG. 4, in various embodiments, a plurality of solar trackers100 can be actuated by a row controller 380 in a solar tracking system400. In this example, four solar trackers 100A, 100B, 100C, 100D can becontrolled by a single row controller 380, which is shown being operablycoupled thereto. As described in more detail herein, in some examples, aplurality of trackers 100 or a subset of trackers 100 can be controlledin unison. However, in further embodiments, one or more trackers 100 ofa plurality of trackers 100 can be controlled differently than one ormore other trackers 100.

While various examples shown and described herein illustrate a solartracking system 400 having various pluralities of rows of trackers 100,these should not be construed to be limiting on the wide variety ofconfigurations of photovoltaic panels 103 and pneumatic actuators 101that are within the scope and spirit of the present disclosure. Forexample, some embodiments can include a single row or any suitableplurality of rows, including one, two, three, four, five, six, seven,eight, nine, ten, eleven, twelve, fifteen, twenty, twenty five, fifty,one hundred, and the like.

Additionally, a given row can include any suitable number of actuators101 and photovoltaic panels 103, including one, two, three, four, five,six, seven, eight, nine, ten, eleven, twelve, fifteen, twenty, twentyfive, fifty, one hundred, two hundred, five hundred, and the like. Rowscan be defined by a plurality of physically discrete tracker units. Forexample, a tracker unit 100 can comprise one or more actuators 101coupled to one or more photovoltaic panels 103.

In some preferred embodiments, the axis of a plurality of solar trackers100 can extend in parallel in a north-south orientation, with theactuators 101 of the rows configured to rotate the photovoltaic panelsabout an east-west axis. However, in further embodiments, the axis oftrackers 100 can be disposed in any suitable arrangement and in anysuitable orientation. For example, in further embodiments, some or allrows may not be parallel or extend north-south. Additionally, in furtherembodiments, rows can be non-linear, including being disposed in an arc,circle, or the like. Accordingly, the specific examples herein (e.g.,indicating “east” and “west”) should not be construed to be limiting.

Also the rows of trackers 100 can be coupled to the ground, over water,or the like, in various suitable ways including via a plurality ofposts. Additionally, while various embodiments described herein describea solar tracking system 400 configured to track a position of the sun ormove to a position that provides maximum light exposure, furtherexamples can be configured to reflect light to a desired location (e.g.,a solar collector), and the like.

FIG. 5 is an exemplary illustration of a set of rows, including a firsttracker 100A and second tracker 100B, with each tracker 100 comprising aplurality of actuators 101 disposed along a common axis (e.g., as shownin FIGS. 1a, 1b and 4) with each actuator 101 comprising a first andsecond bellows 300. More specifically, FIG. 5 illustrates a first solartracker 100A that comprises a first actuator 101AA and a second actuator101AB on which a first set of photovoltaic cells 103A are disposed. Thefirst actuator 101AA of the first tracker 100A comprises east and westbellows 300AE₁, 300AW₁ and the second actuator 100B of the first tracker100AB comprises east and west bellows 300AE₂, 300AW₂.

A second solar tracker 100B comprises a first actuator 101BA and asecond actuator 101BB on which a second set of photovoltaic cells 103Bare disposed. The first actuator 101BA of the second tracker 100Bcomprises east and west bellows 300BE₁, 300BW₁ and the second actuator100BB of the second tracker 100B comprises east and west bellows 300BE₂,300BW₂.

A row controller 380 is shown comprising a pneumatic control unit 384that is operably connected to a pneumatic circuit 382 that drives thebellows 300 of the first and second trackers 101A, 101B via respectivepneumatic lines 390 that are configured to introduce and/or remove fluidfrom the bellows 300 (e.g., via respective bellows branches 392 thatextend from the pneumatic lines 390). More specifically, a first eastpneumatic line 390E₁ is shown being operably connected to the first andsecond east bellows 300AE₁, 300AE₂ of the first tracker 100A.Accordingly, because the first and second east bellows 300AE₁, 300AE₂ ofthe first tracker 100A share a common pneumatic line 390E₁, pneumaticcircuit 382 can drive, introduce fluid to, remove fluid from, and/orotherwise control the first and second east bellows 300AE₁, 300AE₂ inunison via the common pneumatic line 390E₁.

Similarly, a first west pneumatic line 390W₁ is shown being operablyconnected to the first and second west bellows 300AW₁, 300AW₂ of thefirst tracker 100A. Accordingly, because the first and second westbellows 300AW₁, 300AW₂ of the first tracker 100A share a commonpneumatic line 390W₁, pneumatic circuit 382 can drive, introduce fluidto, remove fluid from, and/or otherwise control the first and secondwest bellows 300AW₁, 300AW₂ in unison via the common pneumatic line390W₁.

Accordingly, with the first and second east bellows 300AE₁, 300AE₂ andthe first and second west bellows 300AW₁, 300AW₂ being respectivelyconfigured to be driven in unison, the first and second actuators 101AA,101AB of the first solar tracker 100A can be driven in unison, whichallows for the set of photovoltaic cells 103A coupled to the first andsecond actuators 101AA, 101AB to be rotated laterally about a commonaxis that extends through the first and second actuators 101AA, 101AB.

While this example of FIG. 5 illustrates the first tracker 100Acomprising a first and second actuator 101AA, 101AB, it should be clearthat a plurality of actuators 101 can be driven or controlled in asimilar manner, including trackers 100 having four actuators 101 asillustrated in FIGS. 1a, 1b and 4.

The second tracker 100B is shown having a similar configuration. Morespecifically, a second east pneumatic line 390E₂ is shown being operablyconnected to the first and second east bellows 300BE₁, 300BE₂ of thesecond tracker 100B. Accordingly, because the first and second eastbellows 300BE₁, 300BE₂ of the second tracker 100B share a commonpneumatic line 390E₂, pneumatic circuit 382 can drive, introduce fluidto, remove fluid from, and/or otherwise control the first and secondeast bellows 300BE₁, 300BE₂ in unison via the common pneumatic line390E₂.

Similarly, a second west pneumatic line 390W₂ is shown being operablyconnected to the first and second west bellows 300BW₁, 300BW₂ of thesecond tracker 100B. Accordingly, because the first and second westbellows 300BW₁, 300BW₂ of the second tracker 100B share a commonpneumatic line 390W₂, pneumatic circuit 382 can drive, introduce fluidto, remove fluid from, and/or otherwise control the first and secondwest bellows 300BW₁, 300BW₂ in unison via the common pneumatic line390W₂.

As discussed herein, pneumatics can introduce and/or remove fluid frombellows 300 of one or more actuators 101. For example, pneumatics canactuate a plurality of actuators 101 associated with a solar tracker100. In further examples, pneumatics can actuate a plurality of solartrackers 100 disposed in one or more rows. In various embodiments, apneumatics system (e.g., including the pneumatic circuit 382, pneumaticlines 290, and the like) can comprise a plenum structure for a CADSharness, which in some embodiments can include a high flow capacity mainline with flow restrictions 391 on bellows branches 392 to maintain mainline pressure on long rows. In some embodiments, pneumatic routing canbe disposed on the north side of all actuators of a tracking system 400.In further embodiments, pneumatic routing can be disposed exclusively onthe south side of all actuators of the tracking system 400 or on boththe north and south sides.

In some embodiments, (e.g., as shown in FIG. 5) flow restrictions 391 onsome or all bellows branches 392 can be desirable for equalizing flow(and therefore motion rate) of some or all actuators 101 in a tracker100, a row of trackers 100 or across rows of differing lengths anddiffering pneumatic impedance. The flow restrictions 391 can be tuned toequalize flow within a desired percentage range in accordance withvarious embodiments. Such configurations can equalize motion rate forsome or all of the actuators (keeps panels matched) and can allow formore arbitrary field layout of pneumatic lines 390. Various embodimentscan include a hermetic connector-to-bellow polymer-weld. Furtherembodiments can comprise air brake tubing and fittings for a solarapplication. In some embodiments, the pneumatic circuit 382, using lowpressure, can pump between CADS channels rather than using asource/exhaust system. For example, the system can comprise a rowcontroller 380 that pumps between CADS channels.

Some embodiments can comprise a replenish-leaks-on-power-loss function.For example, an additional low pressure regulator can be added to a rowcontroller 380 or other portion of the solar tracking system 400, with anormally-open valve connecting it to a manifold cross-over. The valvecan be held closed when the system is powered. When power is lost, thevalve opens, replenishing any leaks from an attached high-pressure airtank. This can allow the solar tracking system 400 to maintain a stowposition for an extended period of power-loss, even with leaks in thesystem. For example, FIGS. 8 and 15 of U.S. patent application Ser. No.15/955,506 referenced above and incorporated by reference hereinillustrate example embodiments of row controllers featuring a“replenish-leaks-on-power-loss” function.

In further embodiments the solar tracking system 400 can comprise a windflutter damper-compressor. For example, some configurations can use thefluttering motion of a tracker 100 induced by wind to operate acompressor to augment air supply. One or more pistons (or bellows 300)distributed throughout the tracker 100 can generate additional makeupair to reduce energy consumption while also limiting the magnitude ofany fluttering behavior preventing resonance. Additionally, someembodiments can comprise a double 5/2 valve arrangement, which caninclude a source or exhaust connected to east-output or west-output.

Turning to FIG. 6, a block diagram of a set of elements 600 of oneexample embodiment of a solar tracking system 400 is illustrated, whichincludes a row controller 380 and a first and second solar tracker 100A,100B. The row controller 380 is shown comprising a control device 651, afluid source 652, a fluid source pressure sensor 653, a temperaturesensor 654, a wind sensor 655, a sun sensor 656 and a clock 657. FIG. 14is a block diagram that illustrates another example embodiment of asolar tracking system 400 that comprises an array controller 1400 afirst and second row controller 380 and a first, second, third, fourthsolar tracker 100A, 100B, 100C, 100D.

The embodiments of FIGS. 6 and 14 are merely examples and should not beconstrued to be limiting on the wide variety of architectures of a solartracking system 400 that are within the scope and spirit of the presentdisclosure. For example, some embodiments can include an arraycontroller 1400 that controls one or more row controller 380, which inturn control one or more solar trackers 100. In some embodiments, one orboth of the array controller 1400 and/or row controllers 380 can beabsent, with one or more remaining elements performing sensing and/orcontrol functions.

Additionally, while the array controller 1400, row controller 380 andsolar tracker 100 are shown having a plurality of control and sensingelements, in some examples any shown elements can be absent oradditional control and/or sensing elements can be present. In otherwords, in further examples, any of the array controllers 1400, rowcontroller 380 and solar tracker 100 can be more or less complex and canhave more or fewer elements compared to the examples of FIGS. 6 and 14.

For example, in some embodiments east/west bellows pressure sensors601E, 601W can be disposed at one or more row controller 380 and/orarray controller 1400 and not the solar trackers 100. In furtherembodiments, east/west bellows pressure sensors 601E, 601W can bedisposed at one or more solar tracker 100, which in some embodiments caninclude east/west bellows pressure sensors 601E, 601W associated withone or more actuators 101 of such trackers 100. Still furtherembodiments can include east/west bellows pressure sensors 601E, 601W onevery row of trackers 100, on every couple of rows of trackers 100, andthe like.

Accordingly, in some examples, bellows sensors 601 can be co-located atone or more bellows 300 or can be associated with pneumatic linesassociated with one or more bellows 300. For example, in someembodiments, bellows pressure sensors 601 can be respectively configuredto sense the pressure of a single bellows 300 or the pressure of a groupof bellows 300 including a plurality of east bellows 300E, a pluralityof west bellows 300W, one or more bellows 300 from a plurality oftrackers 100, and the like.

Also, any of the functions or methods described herein can be performedexclusively at one of an array controller 1400, row controller 380 andsolar tracker 100 in some embodiments, or can be performed collectivelyby two or more of an array controller 1400, row controller 380 and solartracker 100. For example, it should be appreciated that embodimentsillustrating functions or method being performed by a row controllershould be construed to be performed alternatively and/or additionally byone or both of an array controller 1400 and row controller.

In various embodiments, the control device 651 can be any suitablecomputing device, which can include a processor, memory, power source,networking hardware, and the like. The control device 651 can storecomputer readable instructions (e.g., software, firmware and the like)on one or more computer readable medium, which can control one or morepneumatic circuits 382, which can in turn drive or control one or moresolar trackers 100 as described in more detail herein. In variousembodiments, a pneumatic control unit 384 can comprise the controldevice 651 or vice versa. In some embodiments, the control device 651can comprise a specialized embedded system or can comprise devices suchas a smartphone, laptop computer, tablet computer or the like.

Some embodiments can comprise solar electrical string powered controlswith no battery backup. For example, the array can be used to powercontrols. In one configuration, a large array 400 can have significantavailable energy even early in the morning before inverters start. A 50kW array (e.g., including eight trackers 100) with 10 W/m{circumflexover ( )}2 irradiance can generate 500 W which can be sufficient topower control systems. Even cloudy days can have more than enough powerto run a compressor. Such embodiments can be employed with or withoutbattery backup. Additionally, the control system can be configured tomove one or more trackers 100 of an array 400 away from vulnerablepositions before energy is lost for the day. In such examples, astow-on-power-loss function can be desirable.

While backup power can be provided via a battery, further embodimentscan comprise a wind turbine to provide backup power (or backup airsupply) during wind events combined with power outages. Risks to a solararray structure can be greatest during extreme wind events, and usingwind to provide energy can help guarantee that energy is available whenneeded.

While some embodiments include the control device 651 being locatedonsite and proximate to one or more solar trackers 100 being controlled,further embodiments can include the control device 651 or portionsthereof being located in a disparate location from the solar trackers100. For example, in some embodiments, control device 651 or portionsthereof can be embodied in one or more physical or virtual computingdevices located away from the solar trackers 100 and control data andsensing data can be communicated to and from such a disparate locationvia various suitable networks, including a cellular network, satellitenetwork, the Internet, a Wi-Fi network, microware network, a lasernetwork, a serial communications system, or the like.

The fluid source 652 can comprise any suitable container for storingfluid. For example, in embodiments where air is used as a fluid forcontrolling bellows 300 of one or more solar trackers 100, the fluidsource 652 can comprise one or more air tank and/or air compressor ofany suitable size and shape. While some embodiments include a fluidsource 652 at the row controller 380, further embodiments can includeone or more fluid sources 652 proximate to one or more solar trackers100. For example, where a plurality of solar trackers 100 are disposedin a row, a fluid source can be disposed at an end of a row.Additionally, where other fluids (e.g., oxygen, nitrogen, water, oil, orthe like) are used, a fluid source 652 can be configured to store suchfluids.

A fluid source pressure sensor 653 can be associated with a fluid source652 and can be configured to sense a pressure associated with the fluidsource 652. Additionally in further embodiments, the pressure sensor 653or other sensors can be configured to sense a volume of fluid presentwithin the fluid source 652. Data associated with a pressure, volume orthe like, of a fluid source can be used as discussed in more detailherein.

The row controller 380 and/or array controller 1400 can comprise variousadditional sensors, including a temperature sensor 654, a wind sensor655, a sun sensor 656, and the like. As discussed herein, a temperaturesensor 654 can be configured to sense a temperature associated with, andcan be configured to determine a fluid volume, or the like, withinvarious portions of a solar tracking system 400, including the fluidsource 652, pneumatic lines 370, pneumatic circuit 382, or the like. Awind sensor 655 can be used to determine wind speed or velocity near therow controller 380, which as discussed herein can be used to determinewhether one or more solar trackers 100 should be moved to a stowedposition to prevent wind damage to the solar trackers 100, whetherrigidity of one or more actuators 101 should be increased or decreased,or whether an alert should be sent to a user regarding wind conditions.

As discussed herein, a solar tracking system 400 can be configured tomove one or more solar trackers 100 to track the position or angle ofthe sun, which can be desirable for maximizing electrical energygenerated by photovoltaic cells 103 of the system 400. In someembodiments, the sun sensor 656 can be used to determine an angle orposition of the sun, which can be used to determine how the solartrackers 100 should be driven as discussed herein. However, in furtherembodiments, a sun sensor 656 can be absent and an angle or position ofthe sun can be determined in other ways.

In various embodiments, a clock 657 can be used to determine an angle orposition of the sun. For example, where the location of the solartracking system 400 and/or components thereof are known (e.g., via GPSor a defined location indicator), astrological charts can be consultedwhich can identify a position or angle of the sun at the location at atime defined by the clock 657. Accordingly, in various embodiments, therow controller 380 can store or otherwise have access to astrologicalcharts that identify what the angle and/or position of the sun will beat various times in the future relative to one or more locations.

A row controller 380 is shown being operably connected to first andsecond solar trackers 100A, 100B in FIG. 6. An array controller 1400 isshown as being operably connected to a first and second row controller380 in FIG. 14. Such an operable connection can include a fluidic and/ordata communication connection with the solar trackers 100 and/or rowcontroller 380 in the case of array controller 1400. For example, afluidic connection can include fluidic lines 390 (see FIGS. 3 and 5)that allow fluid to travel from the array controller 1400 and/or rowcontroller 380 to the one or more solar trackers 100 and/or vice versa.However, in some embodiments, where a fluid source 652 is absent at therow controller 380 and/or array controller 1400, such a fluidicconnection can be absent. For example, where one or more fluid sources652 are located at one or more trackers 100, an operable connectionbetween the row controller 380 and the one or more trackers 100 caninclude only a data communication connection. In another example, one ormore trackers 100 can be self-powered with distributed air compressorsor pumps.

In various embodiments, a data communication connection can include anysuitable wired and/or wireless communication channel that allows data topass from the array controller 1400 to one or more row controller 380,from one or more row controllers 380 to the one or more solar trackers100 and/or vice versa. For example, in some embodiments, sensing datafrom the one or more solar trackers 100 can be communicated to the oneor more row controllers 380 and/or array controller 1400 as discussedherein, which can inform control of the one or more solar trackers 100by a row controller 380 and/or array controller 1400. Additionally oralternatively, control data, or other suitable data (e.g., sensing data)can be communicated to the one or more solar trackers 100 from the rowcontroller 380 and/or array controller 1400. For example, where valvesor other components are present at the one or more trackers 100, suchvalves or components can be controlled via data sent to the one or moretrackers 100 from a row controller 380 and/or an array controller 1400that controls a plurality of row controllers 380.

The solar trackers 100A, 100B can include a respective one or more eastbellows 300AE, 300BE that are associated with one or more respectiveeast bellows pressure sensors 601AE, 601BE. Solar trackers 100A, 100Bcan further include a respective one or more west bellows 300AW, 300BWthat are associated with one or more respective west bellows pressuresensors 601AW, 601BW. For example, as discussed and shown herein (e.g.,in FIGS. 1a, 1b , 4 and 5), a solar tracker 100 can comprise one or moreactuators 101 that each comprise a pair of bellows 300.

In various embodiments, a bellows pressure can be used to determine aninflation/deflation state of the bellows 300, a volume of fluid presentin the bellows, and the like, which can be desirable for monitoring andcontrolling the bellows 300 of a solar tracking system 400. Someembodiments can include one or more pressure sensor 601 associated witha given bellows 300, whereas further embodiments can include pressuresensors associated with only a subset of bellows 300. Pressure sensorscan be disposed proximate to, within or on a bellows 300 or can beoperably coupled to a fluidic line 390 or branch 392 associated with oneor more bellows 300. Bellows pressure data obtained from one or morepressure sensors 601 can be used as discussed in more detail herein.

Additionally, the solar trackers 100A, 100B can comprise variousadditional sensors, including respective inclinometers 603A, 603B,temperature sensors 605A, 605B, wind sensors 607A, 607B, and the like.In various embodiments, an inclinometer 603 can measure an angle ofslope or tilt of the photovoltaic cells 103 associated with a tracker100. For example, an inclinometer 603 can measure an angle of slope ortilt associated with a tracker 100 being in a neutral configuration N,maximum tilts A, B, or any other configurations therebetween, as shownin FIG. 2. Such an identified angle of slope or tilt associated withphotovoltaic cells 103 can be used to determine the position of thephotovoltaic cells 103 of the tracker 100 relative to a position orangle of the sun as discussed in more detail herein.

In some embodiments, a tracker 100 can comprise one or moreinclinometers 603 that can be coupled with or associated with variousportions of a tracker 100, including a top plate 330, actuator 101,photovoltaic cells 103, or the like. Additionally, in furtherembodiments, inclinometers 603 can be absent and/or other suitablesensors can be used to determine an angle of slope or tilt associatedwith photovoltaic cells 103.

As discussed herein, temperature sensors 605A, 605B can be configured todetermine a temperature associated with, and configured to determine afluid volume, or the like, within various portions of a solar trackingsystem 400, including the bellows 300, pneumatic lines 370 or the like.The wind sensors 607A, 607B can be used to determine wind speed orvelocity near solar trackers 100A, 100B, which as discussed herein canbe used to determine whether one or more solar trackers 100 should bemoved to a stowed position to prevent wind damage to the solar trackers100, whether rigidity of one or more actuators 101 should be increasedor decreased, or whether an alert should be sent to a user regardingwind conditions.

In further embodiments, control of a solar tracking system 400 cancomprise temperature and humidity abatement via pneumatic venting, whichcan include opening both fill and vent valves in a row controller 380 orother suitable location and/or using an orificed connection for a rowcontroller 380. Further control system embodiments can comprisemodifying/controlling Voc (open circuit voltage), which can be desirablefor reducing design constraints (e.g., string length) and improve costof inverters, combiner boxes, wiring, and the like. Some embodiments caninclude modifying/controlling Isc (short circuit current), which canreduce design constraints (e.g., current) and can improve the cost ofinverters, combiner boxes, wiring, and the like. Still furtherembodiments can comprise modulating the tracker position to increaseconvection and therefore increase operating voltage and energy output.

In some instances, it can be desirable to reduce the range of motion ofone or more tracker 100, including by limiting the range of motion ofone or more actuator 101, bellows 300, or other suitable portion of atracker 100. For example, limiting the range of motion of one or moretracker 100 can be performed in response to environmental or systemconditions, including elevated wind events, high temperature events, lowtemperature events, and the like. Limiting the range of motion of thetracker 100 can include limiting the range of motion of a tracker 100 toa smaller range of motion compared to a standard range of motion of thetracker 100, with some examples including immobilizing the tracker 100.In some examples, generating a stow of a tracker 100 can includelimiting the range of motion of the tracker 100 in response to a stowevent.

Some embodiments can comprise off-angle tracking for electrical currenthealth inspection. For example, off-angle tracking during highirradiance hours can provide an indication of string level health orhealth of a row controller's worth of panels. In some embodiments, sucha determination can comprise measuring a dip in current output whenportions of an array's tracker are pointed away from the sun. Whereactuators 101 or other portions of a tracker 100 are broken, wiring iswrong, or the like, less of a dip would be observed, which couldindicate an issue with the system in that portion. On the other hand,where actuators 101 or other portions of a tracker 100 are healthy,larger dips during off-sun tracking would be observed, which couldindicate that portion of the system being healthy. Further embodimentscan comprise a pressure/position check to monitor bellows for materialdegradation or other defects.

Some embodiments can use pulse width modulation (PWM) or proportionalvoltage or current control to control valves instead of calculatedopen-time in order to optimally utilize valve cycle life and minimizetracker twist due to long valve open times. Further embodiments can beconfigured to monitor pressures/angles of one or more actuators 101 todetermine a leak location. For example, leaks can be predicted ifpressures/angles in a particular row or tracker 101 are changingdifferently than other rows/trackers, or differently than expected basedon temperature variations and other factors. This can allow leaks to belocated on the row-level or tracker-level. Leaks can be located evenmore precisely, in still further embodiments, with more sensors and/orby learning the system response to leaks as a function of leak location,and adapting control code to recognize patterns that are characteristicof specific leak locations.

While FIG. 6 and the examples discussed herein illustrate specificexample embodiments of a solar tracking system 400, these examplesshould not be construed to be limiting on the wide variety of suitableconfigurations of a solar tracking system 400. For example, any of theelements can be absent in some embodiments, or can be present in aplurality in some embodiments. Additionally, various sensors or elementsshown located at the row controller 380 can alternatively, oradditionally, be located at the solar trackers 100, or vice versa. Also,it should be clear that the example sensors or elements shown in FIG. 4can be replaced or augmented by suitable equivalents or other sensors orelements that provide for similar functionalities.

FIG. 7 illustrates an example of a tracker 100 tracking the position ofsun 700 throughout the day as the sun 700 moves through the sky. Asshown in this example, one or more photovoltaic cells 103 disposed onthe tracker 100 are oriented facing the sun 700 such that tracker axis750, which is perpendicular to the planar face of the photovoltaic cells103, is coincident with the sun 700. Accordingly, as shown in thisexample, the tracker 100 can pivot the photovoltaic cells 103 throughoutthe day (e.g., via actuators 101) to match the angle or location of thesun 700 such that the photovoltaic cells 103 receive maximum sunexposure, which can maximize generation of electrical current by thephotovoltaic cells 103.

However, in further embodiments, a tracker 100 can track the changingposition or angle of the sun 700 in various suitable ways. For example,while the example of FIG. 7 illustrates tracking such that tracker axis750 is coincident with the center of the sun 700, in furtherembodiments, it can be desirable to track the sun 700 with tracker axis750 not being coincident with the center of the sun 700.

For example, in some embodiments, photovoltaic cells 103 can beconfigured with an optimal exposure angle that is not directlyperpendicular to the planar face of the photovoltaic cells 103. Infurther examples, heat generated at the photovoltaic cells 103 viaexposure with tracker axis 750 being coincident with the center of thesun 700 can reduce electrical output, so pointing the tracker 700off-center of the sun can be desirable in some embodiments.Additionally, variables like angle or position of the sun in the sky,weather conditions, or the like can also affect an optimal exposureangle of the photovoltaic cells 103. Accordingly, the examples hereinshould not be construed as limiting.

Turning to FIGS. 8a and 8b , an example of a tracker 100 being in anon-ideal position relative to the sun 700 is shown in FIG. 8a andmoving the tracker 100 to an ideal position with tracker axis 750 beingcoincident with the center of the sun 700 is shown in FIG. 8b . Asdiscussed herein, it can be desirable for solar trackers 100 to trackthe position or angle of the sun 700 to maximize electrical currentoutput by photovoltaic cells 103 on the tracker 100. For example, whereit is determined that the current angle of the photovoltaic cells 103 ofthe tracker 100 is not within a desirable range of an optimal exposureangle of the photovoltaic cells 103, then the tracker 100 can be tiltedso that the photovoltaic cells 103 are positioned within a desirablerange of an optimal exposure angle of the photovoltaic cells 103. Usingthe examples of FIGS. 8a and 8b , in FIG. 8a , it can be determined thatthe tracker 100 is in a non-ideal configuration and can be moved to, orwithin a range of an ideal configuration, for example, by rotating thephotovoltaic cells 103 to the right as shown in FIG. 8 b.

FIG. 9 illustrates an example method 900 of controlling one or moresolar trackers 100 to match the angle or position of the sun. Forexample, in various embodiments a pneumatic control unit 384 (FIGS. 3and 5) or control device 651 (FIG. 6) can be configured to perform themethod 900 of FIG. 9, or the like.

The method 900 begins at 910, where a current angle or position of thesun is determined. For example, in some embodiments a current angle ofthe sun can be determined based on a determined time (e.g., via a clock657 in FIG. 6), a determined or defined position of a tracker 100 orsolar tracking system 400, and based on astrological sun charts thatindicate sun position based on time and location. In furtherembodiments, a current angle or position of the sun can be determinedbased on a sun sensor 656 (FIG. 6) or other suitable method or device.

The method 900 continues at 920 where an ideal angle of the photovoltaicpanels 103 to match the current angle of the sun is determined. Forexample, as discussed herein, such an ideal angle of the photovoltaicpanels 103 can be an angle where the tracker axis 750 is coincident withthe center of the sun 700 (see e.g., FIGS. 7 and 8 b) or other suitableangle, which can include an angle that maximizes the electrical outputof the photovoltaic cells 103.

At 930, a current angle of the photovoltaic cells 103 is determined, andat 940 a difference between the current angle of the photovoltaic cells103 and the ideal angle of the photovoltaic cells 103 is determined. Forexample, as discussed herein, in some embodiments, one or moreinclinometer 603A, 603B of a respective solar tracker 100 can be used toidentify a current angle of the photovoltaic cells 103.

The method 900 continues at 950 where a determination is made whetherthe difference between the current angle of the photovoltaic cells 103and the ideal angle of the photovoltaic cells 103 is within a definedrange. For example, in various embodiments, a tolerance range about anideal angle of the photovoltaic cells 103 can be desirable to allow formovements of the photovoltaic cells 103 in the wind; to conserve energyby not requiring constant movement of the photovoltaic cells 103 tomaintain an exact ideal angle, and the like. For example, such atolerance range can be +/−0.5°, +/−1.0°, +/−2.0°, +/−3.0°, +/−5.0°,+/−10.0° +/−15.0° and the like. Additionally, such a tolerance range canbe symmetrical about an ideal angle as shown in the examples above orcan be asymmetrical. Additionally, such a tolerance range can be staticor dynamic based on various factors, including the current angle of thesun, weather conditions, or the like.

If a determination is made at 950 that the difference between thecurrent angle of the photovoltaic cells 103 and the ideal angle of thephotovoltaic cells 103 is not within a defined range, then the method900 continues to 960 where bellows 300 of one or more actuators 101 ofone or more trackers 100 are inflated and/or deflated to change theangle of the photovoltaic panels 103 toward the determined ideal anglefor the photovoltaic panels 103. However, if at 950 a determination ismade that the difference between the current angle of the photovoltaiccells 103 and the ideal angle of the photovoltaic cells 103 is withinthe defined range, then the method 900 cycles back to 910.

Accordingly, in various embodiments, the position of one or moretrackers 100 can be monitored to determine whether the angle of thetrackers 100 is within a tolerance range of an ideal angle, and if not,the trackers 100 can be actuated to be within the tolerance range. Invarious embodiments, such monitoring and control can be applied to alltrackers 100 within a solar tracking system 400 or one or more subsetsof trackers 100 can be monitored and controlled separately. For example,in some embodiments, it can be desirable to control trackers 100individually based on individual current angles of the trackers 100and/or individual locations of the trackers 100. Also, such monitoringand control can be performed continuously or can be performedperiodically. For example, the method 900 can be performed on a timedelay every second, five seconds, ten seconds, sixty seconds, fiveminutes, fifteen minutes, thirty minutes, or the like.

In various embodiments, solar trackers 100 can enable tweaking ofphotovoltaic system performance characteristics to capture additionalvalue. For example, open circuit voltage of photovoltaic cells 103 canincrease as temperature decreases. Overall system design of someembodiments can be dictated by a maximum voltage that occurs veryinfrequently (e.g., on the coldest mornings of the coldest days of theyear). Intelligent tracking can ameliorate this worst case scenario andcan improve project design economics.

To avoid this scenario, controls of some embodiments can leverageanother principle of photovoltaic cells 103; namely that cell voltagecan also be related to incident light. By pointing the trackers 100somewhere other than directly at the sun, resulting in fewer photonsstriking the photovoltaic cells 103, system voltage is reduced. Whenphotovoltaic cell 103 temperature rises from a combination of ambienttemperature and direct solar heating of the photovoltaic cells 103,system voltage can be reduced further, and the trackers 100 can thenreturn to a position with maximum incident light on the photovoltaiccells 103.

This application can include a combination of design features such asdetecting photovoltaic cells string voltage (e.g., directly or throughquery of some other system device such as an inverter), sensing ofambient temperature or photovoltaic cells' temperature, measurement ofdirect or indirect solar irradiance, and the like.

One benefit of being able to relax the constraint of minimum designtemperature in some embodiments can be the potential for morephotovoltaic cells 103 (and system power) per infrastructure investment.For example, wiring can be done per string, combiner boxes accept amaximum number of strings, and the like. If the number of photovoltaiccells 103 per string increases by 5%, the same amount of power can begenerated with 5% fewer strings, and the infrastructure investmentassociated with those eliminated strings can be avoided. There is alsopotential for reduction in installation labor, as wiring of additionalstrings is much more involved than additional photovoltaic cells 103.

Additionally, higher system voltage can drive additional systemefficiency by reducing the string current at a fixed power output. Thiscan be directly valued in additional energy production, or can enableother system savings through reduction of conductors or the like.Further embodiments can comprise moving photovoltaic cells 103 usingintelligent algorithms to improve performance or system design.

Turning to FIGS. 10 and 11, a state diagram 1000 is shown in FIG. 10with reference to a tracking window 1100 illustrated in FIG. 11. Asshown in FIG. 11, the tracking window 1100 can comprise a negative easttracking window portion 1101 and a positive west tracking window portion1102 that have equal size on opposing sides of a current angle of thesun 1103. A negative east tracking window half 1105 separates an eastinvalid region (EIR) and an east semi-valid region (ESVR). A positivewest tracking window half 1105 separates a west semi-valid region (WSVR)and a west invalid region (WIR). An east out of bound region (EOB) andwest out of bounds region (WOB) are on distal ends of the trackingwindow 1100. An east valid region (EVR) and west valid region (WVR) areseparated by the current angle of the sun 1103.

As discussed herein, control determinations can be made for one or moretrackers 100 based at least in part on a determination of where acurrent angle of the tracker 100 is within the tracking window 1100compared to the current angle of the sun or an ideal tracker targetangle. Turning to FIG. 10, where a tracker 100 is in a locked position1001, if at 1004 the tracker 100 is determined to be in the eastsemi-valid region (ESVR) or in the east invalid region (EIR) and thecurrent destination angle is moving west CAD-MW, then the tracker 100 isactuated to move west 1006. Additionally, where the tracker 100 is in alocked position 1001 and the tracker 100 is determined at 1004 to be inthe east out of bounds region (EOB), then the tracker 100 can beactuated to move west 1006.

For example, a locked position for the tracker 100 can include variousconfigurations, including a stopped configuration where the tracker 100is not being actuated by fluid being introduced and/or removed from thebellows 300 such that the actuators 101 are in a state of equilibrium.Such a locked configuration may or may not include a mechanical lockingmechanism in addition to an equilibrium state between bellows 300 of oneor more actuators 101. In some embodiments, a locked state can comprisevalves associated with the bellows 300 being in a closed configuration.

Also, equilibrium between bellows 300 of an actuator 101 can include arange of pressures. For example, where bellows pressures of X:X generateequilibrium of an actuator 101 such that the actuator 101 does not move,bellows pressures of 2×:2×, 5×:5×, 10×:10× and the like, can alsogenerate equilibrium of an actuator 101. In various embodiments, higherpressures of equilibrium can generate more stiffness in the actuator101, which can be desirable for resisting external forces (e.g., wind)that may cause rotation of the photovoltaic cells 103. However, higherpressures in the bellows 300 can require more fluid and energy, whichmay undesirably consume more energy than necessary and/or cause morewear on bellows 300 or other components of a tracker 100. Accordingly,in some embodiments, it can be desirable to keep relative pressurebetween bellows 300 as low as possible to maintain appropriate functionof the tracker 100.

Returning to the state diagram 1000 of FIG. 10, if the tracker 100 ismoving west 1006 and it is determined at 1008 that the bellows 300 withmost pressure (BMP) has a pressure that is less than a max pressure high(MPH) and where bellows 300 with most pressure (BMP) also has a greaterpressure than a max pressure low (MPL), then at 1010, the west bellows300W of the tracker 100 will vent and the east bellows 300E will fill.

For example, as discussed above, high fluid pressure in bellows 300 cancause undesirable wear on the bellows 300 and can even cause failure ofthe bellows 300 or related components. Accordingly, a max pressure high(MPH) can be defined for the bellows 300, which can be based on amaximum bellows operating pressure that limits undesirable wear on thebellows 300 and is below a pressure that would cause failure of thebellows 300.

Similarly, while low bellows operating pressures can be desirable forconsuming less energy and limiting wear on the bellows 300 and othercomponents, low bellows operating pressures below a certain thresholdcan be inadequate for desirable operation of the actuators 101 of atracker 100. Accordingly, a max pressure low (MPL) can be defined for alowest desirable operating pressure of bellows 300 of a tracker 100.

Some embodiments can comprise variable max pressure high (MPH) and/or amax pressure low (MPL). In one example, material creep reduction caninclude adjusting a control method to have a max bellow pressuredependent on external loads (e.g., reduce pressure when wind speed islow and increase pressure as wind speed increases). The reduced averagepressure over time can limit material creep. In another example, aconstant bellows stress function can include increasing pressure at aflat configuration (e.g., parallel to the ground) to provide morestiffness in stow, which can also provide better accuracy and decreasematerial fatigue. Bellows stress can be inversely proportional to angle,and proportional to pressure. High pressure at low angle in someembodiments can allow for roughly constant bellows material stressthroughout the range of motion of the actuator 101. Additionally,changing peak pressures can be desirable for controlling the resonantmodes and stiffness of a tracker and portions thereof. For example,changing peak pressures can be desirable for withstanding forcegenerated by winds as discussed herein.

Returning to the state diagram 1000 of FIG. 10, where the tracker 100 ismoving west 1006 and it is alternatively determined at 1008 that thetracker 100 is in the east invalid region (EIR) or is in the east out ofbounds region (EOB), then at 1010, the west bellows 300W of the tracker100 will vent and the east bellows 300E will fill. Where, at 1010, thewest bellows 300W of the tracker 100 are venting and the east bellows300E are filling, if it is determined at 1012 that the tracker 100 is inthe west invalid region (WIR) or is in the west out of bounds region(WOB), then the tracker 100 assumes a locked position 1001.

However, where the tracker 100 is moving west 1006 and it isalternatively determined at 1014 that the bellows with most pressure(BMP) has a pressure that is greater than the max pressure high (MPH),then the west bellows 300W of tracker 100 vent at 1016. Where the westbellows 300W of the tracker 100 are venting west at 1016 and it isdetermined at 1018 that the tracker 100 is in the west invalid region(WIR) or is in the west out of bounds region (WOB), then the tracker 100assumes a locked position 1001. Alternatively, if it is determined at1020 that the tracker 100 is in the east invalid region (EIR) or is inthe east out of bounds region (EOB), then at 1010, the west bellows 300Wof the tracker 100 will vent and the east bellows 300E will fill.

However, where the tracker 100 is moving west 1006 and it isalternatively determined at 1022 that the bellows with most pressure(BMP) has a pressure that is less than the max pressure high (MPH), thenthe east bellows 300E of tracker 100 fill at 1024. Where the eastbellows 300E of the tracker 100 are filling at 1024 and it is determinedat 1026 that the tracker 100 is in the west invalid region (WIR) or isin the west out of bounds region (WOB), then the tracker 100 assumes alocked position 1001. Alternatively, if it is determined at 1028 thatthe tracker 100 is in the east invalid region (EIR) or is in the eastout of bounds region (EOB), then at 1010, the west bellows 300W of thetracker 100 will vent and the east bellows 300E will fill.

Similar actions can occur on the left half of the state diagram 1000 ofFIG. 10. For example, where a tracker 100 is in a locked position 1001,if at 1054 the tracker 100 is determined to be in the west semi-validregion (WSVR) or in the west invalid region (WIR) and the currentdestination angle is moving east (CAD-ME), then the tracker 100 isactuated to move east 1056. Additionally, where the tracker 100 is in alocked position 1001 and the tracker 100 is determined at 1054 to be inthe west out of bounds region (WOB), then the tracker 100 can beactuated to move east 1056.

If the tracker 100 is moving east 1056 and it is determined at 1058 thatthe bellows 300 with most pressure (BMP) has a pressure that is lessthan a max pressure high (MPH) and where bellows 300 with most pressure(BMP) also has a greater pressure than a max pressure low (MPL), then at1060, the east bellows 300E of the tracker 100 will vent and the westbellows 300W will fill.

Where the tracker 100 is moving east 1056 and it is alternativelydetermined at 1058 that the tracker 100 is in the west invalid region(WIR) or is in the west out of bounds region (WOB), then at 6010, theeast bellows 300E of the tracker 100 will vent and the west bellows 300Wwill fill. Where, at 1060, the east bellows 300E of the tracker 100 areventing and the west bellows 300W are filling, if it is determined at1062 that the tracker 100 is in the east invalid region (EIR) or is inthe east out of bounds region (EOB), then the tracker 100 assumes alocked position 1001.

However, where the tracker 100 is moving east 1056 and it isalternatively determined at 1064 that the bellows with most pressure(BMP) has a pressure that is greater than the max pressure high (MPH),then the east bellows 300E of tracker 100 vent at 1066. Where the eastbellows 300E of the tracker 100 are venting at 1066 and it is determinedat 1068 that the tracker 100 is in the east invalid region (EIR) or isin the east out of bounds region (EOB), then the tracker 100 assumes alocked position 1001. Alternatively, if it is determined at 1070 thatthe tracker 100 is in the west invalid region (WIR) or is in the westout of bounds region (WOB), then at 1060, the east bellows 300E of thetracker 100 will vent and the west bellows 300W will fill.

However, where the tracker 100 is moving east 1056 and it isalternatively determined at 1072 that the bellows with most pressure(BMP) has a pressure that is less than the max pressure high (MPH), thenthe west bellows 300W of tracker 100 fill at 1074. Where the westbellows 300W of the tracker 100 are filling at 1074 and it is determinedat 1076 that the tracker 100 is in the east invalid region (EIR) or isin the east out of bounds region (EOB), then the tracker 100 assumes alocked position 1001. Alternatively, if it is determined at 1078 thatthe tracker 100 is in the west invalid region (WIR) or is in the westout of bounds region (WOB), then at 1060, the east bellows 300E of thetracker 100 will vent and the west bellows 300W will fill.

For the east filling at 1024 and 1010 and for the west filling at 1074and 1060, the fill routine can have various duty cycles (e.g., 80% onand 20% off), with a total period that can be based on the number ofactuators 101 in a tracker 100. In various embodiments, a pressuremeasurement can be taken at the end of each off period, and if it isdetermined that a bellows 300 is over pressure (e.g., greater than maxpressure high (MPH)), then the off period can be maintained and pressuremeasurements can be maintained until no bellows 300 is over pressure.

As discussed herein, in various embodiments a tracking window 1100 canbe used to control one or more actuators 101 of a solar tracker 100.Referring to the tracking window 1100, in another embodiment, if thetracker 100 is in a valid region (e.g., east or west valid regions (EVR)(WVR)) and the tracker 100 is in a locked position, then valvesassociated with the bellows 300 of the actuators 101 of the tracker 100can be in a closed configuration. However, if the tracker 100 enters asemi-valid region (e.g., east or west semi-valid regions (ESVR) (WSVR)),and the position of the tracker 100 is locked, then the tracker positioncan be unlocked, which can include opening one or more valves associatedwith the bellows 300 of the actuators 101 of the tracker 100. Forexample, at least one valve can open to introduce or remove fluid fromone or more bellows 300 to drive the tracker 100 toward the sun.

However, in some embodiments, where the tracker 100 is determined to bein an out of bounds region (e.g., east or west out of bounds(EOB)(WOB)), then two or more valves can be opened to drive the tracker100 towards the sun. For example, where the tracker 100 crosses into anout-of-bounds region from an invalid region, then a determination can bemade as to what valve is already on and one or more additional valvescan be enabled based on the identity of the first enabled valve.

Additionally, where the tracker 100 is driving towards the sun, then theenabled valves can be disengaged or disabled when the tracker 100reaches an opposite tracking window boundary, which can include thecurrent angle of the sun boundary 1103, the boundary between a valid andsemi-valid region, or the like.

For introducing fluid to bellows 300, in various embodiments, fluid willonly be added to the bellows of maximum pressure (BMP) if such bellows300 has a pressure that is below the bellows max pressure high (MPH) andthe identified pressure of the BMP is considered valid. In variousembodiments, it can be desirable to not increase the pressure of the BMPmore than the MPH, which in various embodiments can be defined as halfof a maximum PSI window.

In various embodiments, movement of actuators 101 by removing orreleasing fluid from bellows 300 can be the implemented method ofactuation unless the pressure identified for the relevant pneumaticcircuit is valid and the BMP has a pressure that is less than the maxpressure low (MPL), which can be defined as half of a maximum PSIwindow. Additionally or alternatively, movement of actuators 101 byremoving or releasing fluid from bellows 300 can be the implementedmethod of actuation unless the pressure identified for the relevantpneumatic circuit is valid and the tracker 100 is determined to be in anout-of-bounds region (e.g., east or west out of bounds (EOB) (WOB)).

Turning to FIG. 12, a method 1200 of identifying a stow event andgenerating a stow in one or more tracker 100 is illustrated. The method1200 begins at 1205, where one or more trackers 100 are tracking theposition of the sun (e.g., as shown in FIG. 7, 8 a, 8 b or 9) and at1210, sensing data from one or more row controller sensors and/or one ormore solar tracker sensors. At 1215, the received sensing data isprocessed to determine whether a stow event is present, and at 1220 adetermination is made whether a stow event is present.

For example, in some embodiments, data regarding wind speed or velocitycan be obtained from wind sensors 655 at a row controller and/or windsensors 607A, 607B of one or more solar trackers 100A, 100B. Such winddata can be evaluated to determine whether it indicates wind conditionsthat pose a threat to one or more trackers 100. In other words, wherethe solar trackers 100 comprise large planar photovoltaic panels 103,wind force can have a strong and undesirable impact on the panels 103,which can potentially cause damage to the photovoltaic panels 103.Accordingly, where wind data identifies wind conditions above a certainthreshold and for a certain time period, it can be determined that astow event is present (i.e., an event that warrants stow of one or moretrackers 100).

Additionally or alternatively, wind data can indicate that actuatorstiffness should be increased to make the actuators 101 of one or moretrackers more rigid to oppose wind force. For example, as discussedherein, opposing bellows 300E, 300W of an actuator can be at equilibriumor generate movement at various opposing pressures, with equilibrium atgreater pressures generating more rigidity in the bellows 300E, 300W andtherefore more rigidity in the actuators 101. However, maintaining thelowest operating pressures possible can be desirable to reduce wear onthe bellows 300 and actuators 101 and also to reduce fluid and powerconsumption. Accordingly, it can be desirable to have actuators 101operate at a minimum operating pressure when no wind is present and todynamically increase pressure, stiffness or rigidity of the actuators101 in response to increasing wind velocity or speed. However, at acertain threshold, it can be desirable to put the trackers 100 into astow configuration to protect the trackers 100 from damage.

Additionally, in various embodiments, the bellows 300 and pressuresexperienced by the bellows 300 can be used to identify whether wind ispresent and whether the wind conditions are such that the tracker 100should be put into a stow configuration for protection against the windor whether increasing the pressure of the bellows 300 to prevent wobblewould be desirable. For example, where a pressure sensor associated witha bellows 300 senses a series of pressure spikes and dips, this can bean indication of wind affecting the position of the photovoltaic cells103 of the tracker 100. If such a sensed condition reaches one or morethresholds (e.g., a maximum or minimum pressure outside of a medianpressure; number of pressure spikes and/or dips of a certain magnitude,and the like), then the tracker 100 can be put into a stow configurationor the pressure of the bellows 300 can be increased to combat wobble.Although such sensing can be performed by wind and/or pressure sensors,in further examples such sensing can be performed by one or more ofinclinometers, changes in power output of photovoltaic cells, or anycombination of pressure sensors, inclinometers, photovoltaic poweroutput, and the like.

In various embodiments, it can be desirable for actuators 101 to beconfigured to stow on power loss. In other words, where the pneumaticssystem loses power, one or more actuators 101 of the system 400 willdefault to a desired safe stow position. For example, using a cross-overvalve, the valve can “normally open” with a spring-return. It is heldclosed when the system is powered. When power is lost the cross-overvalve opens. This can create a “stow on power loss” function for thesystem. In some examples, a cross-over valve can connect the east andwest control air tubes or east and west valve circuits. Air from higherpressure bellows can flow to lower pressure bellows. The cross-overvalve can reduce total system air use by up to 50%, in variousembodiments.

For example, FIG. 15 illustrates an example embodiment of a rowcontroller 380 featuring a “stow on power loss” function. Pressurizedair can be input to a set of solenoid valves 1510 arranged into “east”and “west” valve circuits. The solenoid valves 1510 can be arranged suchthat they can provide the following functions to the row controller 380:fill east, dump east, fill west, and dump west. In some embodiments ofan operating scenario, an electronic control unit 384 can determine aneed to rotate a solar panel 103 or similar object about an axis ofrotation. For example, the electronic control unit 384 can determine aneed to rotate one or more solar panels 103 about an axis of rotationsuch that the top surface of each solar panel 103 stays substantiallyperpendicular to the direction of incoming solar rays as the sun movesacross the sky from east to west, requiring a rotation of the solarpanel 103 toward the west. The electronic control unit 384 can thereforecommand a solenoid valve 310 to open such that pressurized air flowsinto the “east” control lines 390, causing one or more “east” bellows300 to inflate and expand, tilting the solar panel toward the “west”direction. The electronic control unit 384 can also determine thatpressure in the “west” bellows 300 should be released to allow the“west” bellows 300 to deflate and collapse, further allowing a rotationtoward the “west.”

The “east” valve circuits can be independent from control of the “west”valve circuits. This can allows for the simultaneous inflation ordeflation of both the “east” and “west” bellows 300, such that theoverall tension in the mounting system can be controlled. For example,in the event of a wind storm, it can be desirable to inflate both “east”and “west” bellows 300 without causing a change in angle of the solarpanel in order to increase the rigidity or tension in the system tohandle the increased turbulence from the storm. Similarly, it can bedesirable to reduce the overall pressure in both “east” and “west”bellows 300 at the same time.

A fifth solenoid valve 1510V can be a “cross-over” valve which connectsthe “east” and “west” valve circuits. In some embodiments, thecross-over valve 1510V can be a “normally-open” two-way valve, three-wayvalve, or the like. A “normally-open” solenoid valve can be a valvewhich defaults to an open position (such that fluid is allowed to passthrough the valve) upon the removal of power. During a normal operationof row controller 380, cross-over valve 1510V can be energized such thatit closes, stopping fluid flow through the valve to allow independentoperation of the “east” and “west” valve circuits. However, in the eventof the removal of power, cross-over valve 1510V can default to its“normally open” configuration, allowing the pressure in the “east” and“west” valve circuits to equalize, which in turn allows the solar panelsto return to a “zero” position. This configuration of row controller 380can enable a fail-safe mode where some or all controlled tracker rows100 can move to a flat position if the power being supplied to energizevalve 1510V is lost. This configuration can be called “stow on powerloss.”

Accordingly, a stow event can be present based upon various detectedfailures in a solar tracking system 400, including power loss, failureof pneumatic elements (e.g., bellows 300, pneumatic lines 390, apneumatic circuit 382, fluid source 652, valves, or the like), failureof one or more sensors (e.g., pressure sensors 653, 601, temperaturesensors 654, 605, wind sensors 655, 607, sun sensors 656, clock 657,inclinometer 603, and the like), or failure of control systems (e.g.,the control device 651, pneumatic control unit 384, and the like). Invarious embodiments, control systems can execute a stow event or a stowevent can occur automatically upon such a failure. For example, power orpressure loss can automatically result in fluid valves causing a stow ofthe trackers 100 as described herein.

Returning to the method 1200 of FIG. 12, if at 1220 it is determinedthat a stow event is not present, then the method 1200 cycles back to1205 where tracking based on the position of the sun continues. However,if at 1220 it is determined that a stow event is present, at 1225 thebellows 300 of one or more trackers 100 are inflated and/or deflated togenerate a stowed configuration for the one or more trackers 100.

In various embodiments, a stow configuration of a tracker 100 caninclude various suitable configurations. For example, in someembodiments, a stow position for an actuator can be a flat or neutralposition N, or maximum tilt positions A, B (see FIG. 2). In someembodiments, a stow at maximum tilt positions A, B can includepressurizing the tracker against a stop to rigidly fix the tracker 100at one of the maximum tilt positions A, B. In other words, a bellows 300opposing the stop can be inflated to force the actuator 101 or otherportion of the tracker 100 against the stop. The non-opposing bellows300 can be fully deflated in some embodiments to allow for the opposingbellows 300 to provide maximum force against the stop.

In further embodiments, the bellows 300 of one or more actuators 101 canbe inflated to an equilibrium to rigidly fix the bellows 300 in adesired configuration. For example, in some embodiments, inflation ofboth bellows 300E, 300W of an actuator to a maximum fill pressure cangenerate a flat stow or a stow in the neutral configuration N (see FIG.2).

Returning to the method 1200 of FIG. 12, at 1230 sensing data isobtained from one or more row controller sensors and/or one or moresolar tracker sensors, and at 1235, the sensing data is processed todetermine whether a stow event is still present. If at 1240 adetermination is made that a stow event is still present, then at 1245,tracker stow is maintained and the method 1200 cycles back to 1230 wherefurther sensing data is received and the state of the solar trackingsystem 400 is monitored. However, if at 1240 a determination is madethat a stow event is not still present, then at 1250, stow is removedand tracking based on position of the sun is resumed. The method 1200then cycles back to 1210 where monitoring for a further stow eventoccurs.

FIG. 13 illustrates a method 1300 of level-calibrating a solar tracker100 in accordance with an embodiment. For example, when a solar tracker100 is at the factory or set in place via posts 104 (See FIGS. 1a, 1band 2) or other suitable structures, it can be desirable to calibrate or“zero” the system by determining an output of inclinometers 603 (SeeFIG. 6) of one or more trackers 100 that should be defined as where thetracker 100 is level. The method begins at 1310 where a leveling deviceis coupled with the tracker 100 at a position that is parallel to theplane of the photovoltaic panels 103. For example, in some embodiments,a leveling device can be coupled to a top plate 330 of an actuator 101or other suitable structure that is parallel to the plane of thephotovoltaic panels 103.

Additionally, a leveling device can comprise any suitable device thatcan sense and/or present a level status, including a bubble level, adigital level, plumb bob, or the like. In some embodiments, a body of aleveling device can comprise opposing faces disposed at a right angle(e.g. an angle bracket), which can be desirable for coupling to squaredportions of an actuator 101, tracker 100, or the like. In furtherembodiments, the leveling device can comprise a magnet, which can bedesirable for coupling to metal portions of an actuator 101, tracker100, or the like.

Returning to the method 1300, at 1320 one or more bellows 300 of one ormore actuators 101 are inflated and/or deflated to move the photovoltaiccells 103 toward a level position, and if it is determined at 1330 thata level state has not yet been attained the one or more bellows 300 ofone or more actuators 101 are further inflated and/or deflated tofurther move the photovoltaic cells 103 toward a level position.However, where it is determined at 1330 that a level status has beenobtained, then the current inclinometer reading is defined or set asbeing level for the photovoltaic cells 103 of the tracker 100.

For example, setting a current inclinometer reading as being level forthe photovoltaic cells 103 of the tracker 100 can include a manual inputto a device at a row controller 380. Additionally, in some embodiments,a wired or wireless connection with a row controller 380 can communicatea level status or otherwise facilitate calibration of the level statusof a tracker 100.

The described embodiments are susceptible to various modifications andalternative forms, and specific examples thereof have been shown by wayof example in the drawings and are herein described in detail. It shouldbe understood, however, that the described embodiments are not to belimited to the particular forms or methods disclosed, but to thecontrary, the present disclosure is to cover all modifications,equivalents, and alternatives.

In some embodiments, the bellows 300 can be in the form of an elasticvessel which can expand with the introduction of a pressurized fluid,and which can collapse or shrink when the pressurized fluid is released.The term ‘bellows’ as used herein should not be construed to be limitingin any way. For example the term ‘bellows’ as used herein should not beconstrued to require elements such as convolutions or other suchfeatures (although convoluted bellows 300 can be present in someembodiments). As discussed herein, bellows 300 can take on varioussuitable shapes, sizes, proportions and the like.

It should be noted that the figures are not drawn to scale and thatelements of similar structures or functions are generally represented bylike reference numerals for illustrative purposes throughout thefigures. It also should be noted that the figures are only intended tofacilitate the description of the preferred embodiments. The figures donot illustrate every aspect of the described embodiments and do notlimit the scope of the present disclosure.

What is claimed is:
 1. A solar tracker system comprising: a plurality ofsolar trackers, with each solar tracker including: a plurality ofphotovoltaic cells disposed in a common plane and extending along afirst length having a first axis, the plurality of photovoltaic cellscoupled to rails that extend along a second axis that is parallel to thefirst axis; a plurality of actuators coupled to the rails and configuredto collectively rotate the plurality of photovoltaic cells, theplurality of actuators disposed along a common third axis that isparallel to the first and second axis, each of the plurality ofactuators having: a bottom plate; a top plate coupled to the rails; anda first and second bellows extending between and coupled to the topplate and bottom plate; a wind sensor; a row controller operably coupledto and configured to control the plurality of solar trackers, the rowcontroller comprising: a shared pneumatic fluid source; and a pneumaticcircuit having one or more pneumatic lines coupled of a first set ofbellows including the first bellows of the plurality of actuators andone or more pneumatic lines coupled of a second set of bellows includingthe second bellows of the plurality of actuators, the first and secondsets of bellows being mutually exclusive; and an active electronicpneumatic control unit configured to collectively inflate the first setof bellows with fluid from the shared pneumatic fluid source via thepneumatic circuit and configured to separately inflate the second set ofbellows with fluid from the shared pneumatic fluid source via thepneumatic circuit, the active electronic pneumatic control unitconfigured for: actuating the plurality of photovoltaic cells toward afirst determined target ideal angle by at least inflating the first orsecond set of bellows with fluid from the shared pneumatic fluid sourcevia the pneumatic circuit, the actuating based at least in part ondetermining that a determined difference between a first determinedcurrent angle of the plurality of photovoltaic cells and the firstdetermined target ideal angle of the plurality of photovoltaic cells isoutside of a tolerance range, determining that a stow event is presentbased at least in part on a first set of wind velocity data obtainedfrom the wind sensor including wind velocity data above a definedthreshold and for a defined time period that indicates wind conditionsbeing present that pose a threat to at least one of the plurality ofsolar trackers, the threat to at least one of the plurality of solartrackers including the wind conditions potentially causing physicaldamage to the at least one of the plurality of solar trackers, inresponse to determining that the stow event is present, actuating theplurality of photovoltaic cells toward a stow configuration target angleby at least inflating the first or second set of bellows with fluid fromthe shared pneumatic fluid source via the pneumatic circuit, uponreaching the stow configuration target angle, inflating the first andsecond set of bellows to an equilibrium to rigidly fix the plurality ofphotovoltaic cells at the stow configuration target angle, while theplurality of photovoltaic cells are rigidly fixed at the stowconfiguration target angle, determining that the stow event is no longerpresent based at least in part on a second set of wind velocity dataobtained from the wind sensor including wind velocity data below adefined threshold and for a defined time period that indicates windconditions being present that no longer pose the threat to the pluralityof solar trackers, and in response to determining that the stow event isno longer present, actuating the plurality of photovoltaic cells towarda second determined target ideal angle by at least inflating the firstor second set of bellows with fluid from the shared pneumatic fluidsource via the pneumatic circuit, the actuating based at least in parton determining that a determined difference between a second determinedcurrent angle of the plurality of photovoltaic cells and the seconddetermined target ideal angle of the plurality of photovoltaic cells isoutside of the tolerance range.
 2. The solar tracker system of claim 1,further comprising determining that a stow event is present based atleast in part on one or more of: a detected power loss; a detectedfailure of pneumatic elements; a detected failure of one or moresensors; and a detected failure of a control system.
 3. The solartracker system of claim 1, wherein the stow configuration target angleis an angle of the plurality of photovoltaic cells between two maximumtilt position angles where the plurality of solar trackers are forcedagainst a respective hard stop at the maximum tilt position angles. 4.The solar tracker system of claim 1, wherein the active electronicpneumatic control unit is configured to operate the plurality ofactuators at a minimum operating pressure when no wind is present andconfigured to dynamically increase stiffness of the plurality ofactuators in response to increasing wind speed by dynamically increasingoperating pressure of the plurality of actuators.
 5. A solar trackersystem comprising: a plurality of solar trackers, with each solartracker including one or more solar panels and a plurality of actuatorscoupled to the one or more solar panels, each of the plurality ofactuators having first and second elastic vessels; a wind sensor; and anelectronic control unit configured to collectively inflate a first setof the first elastic vessels with fluid from a fluid source andconfigured to separately inflate a second set of the second elasticvessels with fluid from the fluid source, the electronic control unitconfigured to: determine that a stow event is present based at least inpart on a first set of wind speed data obtained from the wind sensorthat indicates wind conditions being present that pose a threat to atleast one of the plurality of solar trackers, the threat to at least oneof the plurality of solar trackers including the wind conditionspotentially causing physical damage to the at least one of the pluralityof solar trackers, in response to determining that the stow event ispresent, actuate the one or more solar panels toward a stowconfiguration target angle by at least inflating the first or second setof elastic vessels with fluid from the fluid source, and upon reachingthe stow configuration target angle, inflate the first and second set ofelastic vessels to rigidly fix the one or more solar panels at the stowconfiguration target angle.
 6. The solar tracker system of claim 5,wherein the determining that a stow event is present based at least inpart on the first set of wind speed data obtained from the wind sensorthat indicates wind conditions being present that pose the threat to atleast one of the plurality of solar trackers includes determining thatthe first set of wind speed data indicates wind speed above a definedwind speed threshold and for a defined time period.
 7. The solar trackersystem of claim 5, wherein the electronic control unit is furtherconfigured to: while the one or more solar panels are fixed at the stowconfiguration target angle, determining that the stow event is no longerpresent based at least in part on a second set of wind speed dataobtained from the wind sensor including wind speed data below a definedthreshold and for a defined time period that indicates wind conditionsbeing present that no longer pose the threat to the plurality of solartrackers.
 8. The solar tracker system of claim 7, wherein the electroniccontrol unit is further configured to: in response to determining thatthe stow event is no longer present, actuating the one or more solarpanels toward a determined target ideal angle by at least deflating orinflating the first or second set of elastic vessels with fluid from thefluid source, the actuating based at least in part on determining that adetermined difference between a determined current angle of the one ormore solar panels and the determined target ideal angle of the one ormore solar panels is outside of a tolerance range.
 9. The solar trackersystem of claim 5, wherein the electronic control unit is furtherconfigured to: determine that an alert should be sent to a userregarding wind conditions based at least in part on determining that afirst set of wind speed data indicates wind speed above a defined windspeed threshold and for a defined time period; and send an alert to theuser regarding wind speed proximate to the solar tracker systempotentially causing physical damage to the at least one of the pluralityof solar trackers.
 10. A solar tracker system comprising: one or moresolar trackers, with each solar tracker including one or more panels andone or more actuators coupled to the one or more panels, each of the oneor more actuators having a first vessel and a second vessel; and anelectronic control unit configured to inflate the first vessel withfluid from a fluid source and configured to separately inflate thesecond vessel with fluid from the fluid source, the electronic controlunit configured to: determine that a stow event is present based atleast in part on a first set of environmental data obtained from anenvironmental sensor that indicates environmental conditions beingpresent that pose a threat to the one or more solar trackers, and inresponse to determining that the stow event is present, actuate the oneor more panels toward a stow configuration target angle by at leastinflating the first or second vessels with fluid from the fluid source.11. The solar tracker system of claim 10, wherein the electronic controlunit is further configured to: upon reaching the stow configurationtarget angle, inflate the first and second vessels to fix the one ormore panels at the stow configuration target angle.
 12. The solartracker system of claim 10, wherein the threat to the at least one ofthe one or more solar trackers including the environmental conditionspotentially causing physical damage to the one or more solar trackers.13. The solar tracker system of claim 10, wherein the environmentalsensor comprises a wind sensor.
 14. The solar tracker system of claim10, wherein first set of environmental data comprises wind speed data orwind velocity data.
 15. The solar tracker system of claim 10, whereinthe determining that the stow event is present is based at least in parton a first set of wind speed data obtained from a wind sensor thatindicates wind conditions being present that pose the threat to the oneor more solar trackers, and wherein determining that the stow event ispresent further includes determining that the first set of wind speeddata indicates wind speed above a defined wind speed threshold.
 16. Thesolar tracker system of claim 10, wherein the electronic control unit isfurther configured to: while the one or more panels are fixed at thestow configuration target angle, determining that the stow event is nolonger present based at least in part on a second set of environmentaldata obtained from the environmental sensor; and in response todetermining that the stow event is no longer present, actuating the oneor more panels toward a determined target ideal angle by at leastdeflating or inflating the first or second vessel, the actuating basedat least in part on determining that a determined difference between adetermined current angle of the one or more panels and the determinedtarget ideal angle of the one or more panels is outside of a tolerancerange.
 17. The solar tracker system of claim 10, further comprisingdetermining that a stow event is present based at least in part on oneor more of: a detected power loss; a detected failure of a pneumaticelement; a detected failure of one or more sensors; and a detectedfailure of a control system.
 18. The solar tracker system of claim 10,wherein the stow configuration target angle is an angle of the one ormore panels between two maximum tilt position angles where the one ormore solar trackers are forced against a respective hard stop at themaximum tilt position angles.
 19. The solar tracker system of claim 10,wherein the electronic control unit is configured to operate the one ormore actuators at a minimum operating pressure when no wind is presentand configured to dynamically increase stiffness of the one or moreactuators in response to increasing wind speed by dynamically increasingoperating pressure of the one or more actuators.
 20. The solar trackersystem of claim 10, wherein the electronic control unit is furtherconfigured to: determine that an alert should be sent to a userregarding environmental conditions based at least in part on a secondset of data from the environmental sensor; and send an alert to the userregarding environmental conditions proximate to the solar tracker systempotentially causing physical damage to the one or more solar trackers.